Daily age determination and growth rates of freshwater fish throughout a regulated lotic system of the Murray‐Darling Basin Australia

2018 ◽  
Vol 35 (2) ◽  
pp. 457-464
Author(s):  
Jerom R. Stocks ◽  
Karen F. Scott ◽  
Dean M. Gilligan
Keyword(s):  
Freshwater Fish ◽  
Growth Rates ◽  
Age Determination ◽  
Murray Darling Basin ◽  
Lotic System

Conservation of an inauspicious endangered freshwater fish, Murray hardyhead (Craterocephalus fluviatilis), during drought and competing water demands in the Murray–Darling Basin, Australia

2013 ◽  
Vol 64 (9) ◽  
pp. 792 ◽  
Author(s):  
Iain M. Ellis ◽  
Daniel Stoessel ◽  
Michael P. Hammer ◽  
Scotte D. Wedderburn ◽  
Lara Suitor ◽  
...  
Keyword(s):  
Freshwater Fish ◽  
Environmental Water ◽  
River Regulation ◽  
Isolated Populations ◽  
Conservation Units ◽  
European Settlement ◽  
Water Demands ◽  
Murray Darling Basin ◽  
Conservation Concern ◽  
Australian Freshwater

Approximately 40% of Australian freshwater fish species are of conservation concern, largely because of the impacts of river regulation, habitat fragmentation and alien fishes. Murray hardyhead is a threatened fish endemic to the southern Murray–Darling Basin in Australia, which has declined significantly in range and abundance since European settlement. Conservation of the species has relied largely on environmental watering of off-channel wetlands where isolated populations persist. This became problematic during recent drought (1997–2010) because of competing demands for limited water, and resentment towards environmental watering programs from communities that themselves were subject to reduced water entitlements. In response, emergency conservation measures prioritised the delivery of environmental water to minimise applied volumes. Captive maintenance programs were established for fish rescued from four genetically distinct conservation units, with varying levels of breeding success. Several translocations of wild and captive-bred fish to surrogate refuge sites were also conducted. Future recovery of the species should secure existing natural and stocked populations and translocate fish to additional appropriate sites to spread risk and reinstate natural pathways for dispersal. The approach to the conservation of Murray hardyhead during extreme environmental conditions provides insights to inform the management of fishes in other drought-prone regions of the world.

scholarly journals A review of on-ground recovery actions for threatened freshwater fish in Australia

2013 ◽  
Vol 64 (9) ◽  
pp. 775 ◽  
Author(s):  
Mark Lintermans
Keyword(s):  
Freshwater Fish ◽  
Threatened Species ◽  
Management Interventions ◽  
Murray Darling Basin ◽  
Social Challenge ◽  
Eastern Australia ◽  
Prolonged Drought ◽  
Conservation Concern ◽  
Habitat Enhancement ◽  
General Conservation

Freshwater fish are a highly threatened group and recovery of these threatened species is an increasingly difficult ecological and social challenge. There are many different on-ground recovery actions available to managers, but no synthesis of what, how or why these recovery actions have been deployed. The present paper reviews 428 reported on-ground recovery actions from a survey of practitioners of threatened freshwater-fish recovery in Australia. Recovery actions were grouped into 12 categories, with the most commonly utilised recovery categories being harvest control, translocation, habitat enhancement and stock enhancement. Major drivers of recovery actions were general conservation concern, recovery plans and emergency responses. The number of recovery actions grew significantly in the decade beginning 2000 as the impacts of prolonged drought in south-eastern Australia intensified. In all, 58% of recovery actions occurred in the Murray–Darling Basin, although this region holds only 27% of the 74 listed threatened freshwater fish in Australia. Few or no recovery actions were reported for many species, and few actions occurred in northern or western parts of the country. More than 80% of recovery actions reportedly had some form of monitoring. The diversity of management interventions is reviewed, and patterns and issues are identified to guide future recovery efforts.

Age and growth of Murray Cod, Maccullochella peelii (Perciformes: Percichthyidae), in the Lower Murray-Darling Basin, Australia, from thin-sectioned Otoliths

1992 ◽  
Vol 43 (5) ◽  
pp. 983 ◽  
Author(s):  
JR Anderson ◽  
AK Morison ◽  
DJ Ray
Keyword(s):  
Growth Rates ◽  
Growth Parameters ◽  
Age And Growth ◽  
Average Error ◽  
Fish Length ◽  
Exponential Relationship ◽  
Thin Sections ◽  
False Rings ◽  
Murray Darling Basin ◽  
Murray Cod

Transverse thin sections (0.5 mm thick) of sagittal otoliths from 290 Murray cod up to 1400 mm in total length and 47.3 kg in weight were used to establish the age and growth of cod in the lower Murray-Darling Basin, including comparisons of recent (1986-91) and past (1949-51) growth rates and growth in different waters. The maximum estimated age was 48 years. Quantitative and qualitative analysis of the seasonal changes in otolith marginal increments showed that annuli in fish of all ages were laid down each spring, and 1 October was assigned as the birthday. The thin-sectioning method was validated by comparing age estimates for 55 Murray cod from Lake Charlegrark (age 0-21 years), which had been validated by using burnt and polished half-otoliths. The new method had an accuracy of 96.4% and it offers major advantages in ease of preparation, reading, and batch-handling of large numbers of otoliths. The precision of the method, estimated as an average error for four readers, was 5.4% (3.0% after ignoring discrepancies in relation to annuli on otolith edges). There was a linear relationship between otolith weight and fish age and an exponential relationship between otolith weight and fish length. Both otolith length and otolith width reached an asymptote at about 15 years, when fish length also approached its maximum. However, otolith thickness continued to increase throughout the life of the fish and, after about 15 years, contributed most to the increase in otolith weight. This confirmed that otoliths continued to grow in thickness and that annuli were laid down throughout life, and that cod could be aged reliably to the maximum age. The annulus pattern is very clear and distinct, and the reading techniques are fully described, including recognition of 'larval' and 'false' rings. Various differences were found in the growth rates, and the length-weight relationships for males and females, for cod caught in 1986-91 and those caught in 1949-51, and various subpopulations are discussed. The von Bertalanffy growth parameters (all individuals combined) were estimated at L∞ = 1202 mm, k=0.108 and t0= -0.832. The availability of a reliable ageing method provides the first opportunity to determine year of birth and thus to examine the age structure of populations and to effectively manage cod populations that have declined in abundance.

scholarly journals Wilhelm Blandowski’s contribution to ichthyology of the Murray-Darling Basin, Australia

2009 ◽  
Vol 121 (1) ◽  
pp. 90
Author(s):  
Paul Humphries
Keyword(s):  
New Species ◽  
Freshwater Fish ◽  
19Th Century ◽  
Significant Contribution ◽  
Aboriginal People ◽  
Habitat Size ◽  
Scientific Establishment ◽  
Murray Darling Basin ◽  
Written Descriptions

Wilhelm Blandowski is best known for the scandal that surrounded his attempts to name a number of new species of freshwater fish after prominent members of the Victorian scientific establishment. Although this 19th Century anecdote is diverting, it belies, I believe, the significant contribution that the first paid Victorian government zoologist made to the ichthyology of the Murray-Darling Basin. Although his claim to new species was exaggerated, his collections, assisted by Gerard Krefft were the most diverse to that date. There is no doubt – because Blandowski tells us as much – that the expedition’s success in collecting so many species, as well as information on distribution, habitat, size and diet, can be attributed to the knowledge of the local Aboriginal people, the Nyeri Nyeri. That Blandowski realised that this knowledge existed and acknowledged it, is unusual for the time. The information provided, although broadly consistent with what we know of the species’ current habits, is scanty and there is some uncertainty as to the location where most of the species were collected. Interpretations based on illustrations, written descriptions and extant specimens suggest that many species that were collected in 1856/57 no longer occur in that region of the Murray-Darling Basin. Blandowski’s collections also hint at the possibility that the distribution of the spotted galaxias, Galaxias truttaceus Valenciennes 1846, normally considered coastal, may have formerly extended much further up into freshwater.

How Old are Tropical Trees? the Persistence of a Myth

IAWA Journal ◽  
1999 ◽  
Vol 20 (3) ◽  
pp. 255-260 ◽  
Author(s):  
Martin Worbes ◽  
Wolfgang Johannes Junk
Keyword(s):  
South America ◽  
Growth Rates ◽  
Age Determination ◽  
Tropical Trees ◽  
Pioneer Species ◽  
Annual Rings ◽  
Hollow Trees ◽  
Cariniana Legalis ◽  
Direct Counting ◽  
Age Determinations

The recent report of ancient trees in the Amazon region (Chambers et al. 1998) with a maximum radiocarbon dated age of about 1400 years for the long-living pioneer species Cariniana micrantha is discussed in the light of dendrochronological age determinations from Africa and South America together with the results of indirect age estimations from other sources. There is a tendency in the literature to considerably overestimate the maximum ages of tropical trees. Age determination by the direct counting of annual rings and making estimations for hollow trees by measuring growth rates and diameters result in ages between 400 and 500 years for the largest trunk dimensions, e.g. in Cariniana legalis.

Validation of the use of thin-sectioned Otoliths for determining the age and growth of Golden Perch, Macquaria ambigua (Perciformes: Percichthyidae), in the Lower Murray-Darling Basin, Australia

1992 ◽  
Vol 43 (5) ◽  
pp. 1103 ◽  
Author(s):  
JR Anderson ◽  
AK Morison ◽  
DJ Ray
Keyword(s):  
Growth Rates ◽  
Total Weight ◽  
Birth Date ◽  
Fish Length ◽  
Thin Sections ◽  
Continuous Growth ◽  
Total Length ◽  
Murray Darling Basin ◽  
The Mean ◽  
Age Estimates

Golden perch, Macquaria ambigua, from the Murray-Darling Basin were aged by using transverse thin sections of their sagittal otoliths. Samples from 889 fish were obtained from riverine and lacustrine habitats and from wild and stocked populations. Error in the precision of age estimates (calculated as the mean percentage error of the independent age estimates of four readers) was 5.6% (3.9% after allowing for discrepancies in relation to the annual mark on the edge of the otolith). Validation was accomplished by using a combination of analysis of the progression of modes in length-frequency distributions, qualitative and quantitative marginal-increment analysis, and analysis of age estimates of fish from populations with a known stocking history. The technique was validated for fish up to 8 years of age (455-545 mm total length, 1695-3988 g total weight), and the greatest recorded age was 16 years (530-600 mm total length, 2607-4050 g total weight). Annual marks become visible in otolith sections in most fish of all ages in October, and 1 October was designated as the birth date. A description of our method of reading sections of golden perch otoliths, including recognition of false annual marks, is given. Otolith length, width and thickness increased linearly with fish length and with loglo(fish age), whereas otolith weight increased linearly with fish age and exponentially with fish length. The continuous growth of the otoliths and the consistency in the appearance of annual marks support the accuracy of estimates up to the maximum recorded age. The mean length-at-age and the parameters of the length-weight relationship were estimated. The von Bertalanffy growth parameters were also estimated (L∞ =507 mm, to=0.420 years, K=0.454). No significant differences were found in growth rates or length-weight relationships between males and females. However, growth (particularly in weight) was highly variable among sites and years, and slow-growing 5-year-olds may be shorter than fastgrowing 1-year-olds. Ages were estimated for a sample of 86 golden perch caught between 1949 and 1951 but a comparison of growth rates between these and more recent collections was inconclusive.

Daily Growth Rates as Indicated by Valve Ridges in Postlarval Giant Scallop (Placopecten magellanicus) (Bivalvia: Pectinidae)

1993 ◽  
Vol 50 (3) ◽  
pp. 456-464 ◽  
Author(s):  
G. Jay Parsons ◽  
Shawn M. C. Robinson ◽  
John C. Roff ◽  
Michael J. Dadswell
Keyword(s):  
Growth Rates ◽  
Larval Fish ◽  
Shell Height ◽  
Age Determination ◽  
Growth Patterns ◽  
Placopecten Magellanicus ◽  
Short Term ◽  
Daily Growth ◽  
Alizarin Red ◽  
Growth Increments

Postlarval giant scallop (Placopecten magellanicus) were examined for daily growth ridges and growth rates by marking the dissoconch shell with Alizarin red dye. The surface of the left valve of postlarvae was composed of concentric ridges, each consisting of a series of irregularly shaped raised nodules. Ridges were clear and distinct in newly settled scallop between ≈0.25 and 2.0 mm shell height. The shell of postlarvae >2 mm was pigmented and ribbed and ridges were no longer distinguishable. Estimated age was significantly correlated with actual age, suggesting that growth ridges were produced daily, under the environmental conditions of Passamaquoddy Bay. Mean growth rate ranged from 32 to 57 μm∙d−1 and was proportional to size and age, but growth of individual scallop showed no coherence in their daily growth patterns. The short-term growth ridges in postlarval giant scallop can be used to determine age and can be applied to comparative growth, mortality, and recruitment studies of newly settled individuals <2.0 mm (≈40 d old postsettlement). The high accuracy and precision of age determination for postlarval scallop differs from studies of short-term internal growth increments of bivalve shells and larval fish otoliths.

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